Method for Supporting the Driver of a Road-Bound Vehicle in Guiding the Vehicle

ABSTRACT

The invention relates to a method for supporting the driver of a road-bound vehicle in guiding the vehicle, in which the vehicle environment, in particular the markings that delimit the lanes of a road and traffic signs, are detected by means of an environment sensor system ( 1 ) and evaluated by means of an image evaluation system. According to the invention, the image data of the environment sensor system ( 1 ) are evaluated with regard to lane-relevant information, wherein the detected lane-relevant information is evaluated by means of data that are stored in a memory device ( 2 a) and that indicate country-specific lane markings, and a first country estimation signal (S 1 ) corresponding to the current location of the vehicle is generated, and/or the image data of the environment sensor system ( 1 ) are evaluated with regard to traffic-sign-relevant information, wherein the detected traffic-sign-relevant information is evaluated by means of data that are stored in a memory device ( 3 a) and that indicate country-specific traffic signs, and a country estimation signal (S 2 ) corresponding to the current location of the vehicle is generated, and/or the image data of the environment sensor system ( 1 ) are evaluated with regard to the recognition of license plates of motor vehicles ( 4 ) and a country estimation signal (S 3 ) is generated by means of an analysis by frequency. A country signal (L) that indicates the current location of the vehicle is generated from one country estimation signal (S 1,  S 2,  S 3 ) or from several country estimation signals (S 1,  S 2,  S 3 ) by means of a microprocessor ( 5 ), wherein a driver information device ( 6 ) for outputting country-specific information regarding the longitudinal and transverse guidance of the vehicle is activated by means of the country signal (L) and/or the country signal (L) is fed to at least one driver assistance system ( 7 ) that supports the longitudinal and/or transverse guidance of the vehicle. The invention further relates to a device for performing the inventive method.

The invention relates to a method for supporting the driver of a road-bound vehicle in guiding the vehicle according to the preamble of Patent claim 1. The invention further relates to a device for performing the inventive method.

Driver assistance systems that support the driver in longitudinal and/or transverse guidance or independently perform longitudinal and/or transverse guidance are known, e.g., ACC (Adaptive Cruise Control), LDW (Lane Departure

Warning), ISA (Intelligent Speed Adaption), or lane detection systems.

The essential task of such systems consists in reliably detecting the course and the lateral boundaries of the used lane, particularly in reliably (i.e., particularly at a low rejection rate) identifying traffic signs with regard to the ISA function.

From DE 103 11 240 A1 a vehicle tracking device is known, in which markings that delimit the pavement or the lanes are detected and evaluated by means of an environment sensor system and by means of evaluation means, wherein country-specific marking regulations for pavement marking are stored in a memory device. A navigation device by means of which the position of the vehicle is determined is provided for using these data.

Furthermore, in the method known from DE 103 43 941 A1, the changing traffic regulations are outputted after the crossing of a national boundary or when a national boundary is going to be crossed. This comprises, e.g., a regulation for a light control of the vehicle or a regulation for a speed limit of the vehicle. The position of the vehicle is determined by means of a navigation device (particularly by means of a satellite) in this known method as well.

A method for traffic sign recognition including the additional use of navigation data is known from, e.g., EP 1 114 371 B1. In this method, traffic signs are recognized in a first step, whereafter vehicle-locating navigation data are provided that are compared with each other and, if necessary, updated. For this purpose, these data are fed to an evaluation unit, a currently valid speed limit is determined, and, if necessary, control signals for a driver assistance system are generated.

However, these known methods or systems do not satisfactorily solve the problem of driver assistance systems having to adapt to country-specific features, which concerns, e.g., lane detection systems (e.g., LDW) or traffic sign recognition. For example, the recognition performance of the classifiers used in traffic sign recognition systems could be improved if a piece of information about the country in which the vehicle is traveling were available. Lane detection algorithms could also benefit from such a piece of information by using it, e.g., to eliminate any ambiguities with regard to pavement markings.

It is therefore the object of the invention to provide an improved method for supporting the driver of a road-bound vehicle in guiding his or her vehicle of the type mentioned at the beginning, by means of which it is particularly possible to reduce the number of incorrect detections with regard to lane detection and traffic sign recognition.

This object is achieved by a method with the features of Patent claim 1.

According to the invention, this method for supporting the driver of a road-bound vehicle in guiding the vehicle, in which the markings that delimit the lanes of a road and traffic signs are detected by means of an environment sensor system and evaluated by means of an image evaluation system, provides that

the image data of the environment sensor system are evaluated with regard to lane-relevant information,

the detected lane-relevant information is evaluated by means of data that are stored in a memory device and that indicate country-specific lane markings, and a first country estimation signal corresponding to the current location of the vehicle is generated,

a country signal that indicates the current location of the vehicle is generated from the country estimation signal by means of a microprocessor, and

a driver information device for outputting country-specific information regarding the longitudinal and transverse guidance of the vehicle is activated by means of the country signal and/or the country signal is fed to at least one driver assistance system that supports the longitudinal and/or transverse guidance of the vehicle.

The country signal is preferably fed to a traffic sign recognition system and/or to a license plate determination system.

Furthermore, the object is also achieved by a method with the features of Patent claim 3.

According to the invention, this method provides that

the image data of the environment sensor system are evaluated with regard to traffic-sign-relevant information,

the detected traffic-sign-relevant information is evaluated by means of data that are stored in a memory device and that indicate country-specific traffic signs, and a second country estimation signal corresponding to the current location of the vehicle is generated,

a country signal that indicates the current location of the vehicle is generated from the country estimation signal by means of a microprocessor, and

a driver information device for outputting country-specific information regarding the longitudinal and transverse guidance of the vehicle is activated by means of the country signal and/or the country signal is fed to at least one driver assistance system that supports the longitudinal and/or transverse guidance of the vehicle.

The country signal is preferably fed to a lane detection system and/or to a license plate determination system.

Furthermore, the object is also achieved by a method with the features of Patent claim 5.

According to the invention, this method provides that

the image data of the environment sensor system are evaluated with regard to the recognition of license plates of motor vehicles and a country estimation signal is generated by means of an analysis by frequency,

a country signal that indicates the current location of the vehicle is generated from the country estimation signal by means of a microprocessor, and

a driver information device for outputting country-specific information regarding the longitudinal and transverse guidance of the vehicle is activated by means of the country signal and/or the country signal is fed to at least one driver assistance system that supports the longitudinal and/or transverse guidance of the vehicle.

The country signal is preferably fed to a traffic sign recognition system and/or to a lane detection system and/or to a license plate determination system.

Finally, the object is also achieved by a method with the features of Patent claim 7.

According to the invention, this method for supporting the driver of a road-bound vehicle in guiding the vehicle, in which the markings that delimit the lanes of a road and traffic signs are detected by means of an environment sensor system and evaluated by means of an image evaluation system, provides that

the image data of the environment sensor system are evaluated with regard to lane-relevant information,

the detected lane-relevant information is evaluated by means of data that are stored in a first memory device and that indicate country-specific lane markings, and a first country estimation signal corresponding to the current location of the vehicle is generated,

the image data of the environment sensor system are evaluated with regard to traffic-sign-relevant information,

the detected traffic-sign-relevant information is evaluated by means of data that are stored in a second memory device and that indicate country-specific traffic signs, and a second country estimation signal corresponding to the current location of the vehicle is generated,

a country signal that indicates the current location of the vehicle is generated from the first country estimation signal and the second country estimation signal by means of a merger module, and

a driver information device for outputting country-specific information regarding the longitudinal and transverse guidance of the vehicle is activated by means of the country signal and/or the country signal is fed to at least one driver assistance system that supports the longitudinal and/or transverse guidance of the vehicle.

In this method, for determining a country estimation signal from markings that delimit the lanes of a road or for determining a first country estimation signal, lane-relevant information is detected as features, said features describing the pavement. Such features are, e.g., lane markings, characteristic roadside structures, keep-out areas, or other country-specific pavement markings.

Detailed characteristics of such features are, e.g.:

width of lane marking,

blanking intervals and segment lengths existing when lane markings are broken lines,

color of marking,

Botts' dots (lane markings) used in the USA,

characteristics of multiple markings as a combination of the above-mentioned features,

geometric proportions of markings (e.g., distance between left and right markings, width proportions in multiple markings),

special signs, e.g., direction signs located at exit ramps or where passing is prohibited,

text and characters on the road,

color of pavement,

markings on tollbooth approaches,

traffic island markings,

structural characteristics of curbstones,

structural characteristics of crash barriers,

appearance of delineators (color, geometry, properties of reflectors), and

color of road lighting.

Although some countries partially agreed on a standardization of traffic signs (Vienna Convention on Road Signs and Signals and Agreement Supplementing the Convention on Road Signs and Signals), there are considerable differences between the individual countries with regard to traffic sign characteristics. Therefore, for determining a country estimation signal from image data of traffic signs or for determining the second country estimation signal, the following features (which are examples) are detected as traffic-sign-relevant information:

country-specific traffic sign characteristics, e.g., with regard to shape, size, color, font and graphics characters, or pictographs in speed limit signs,

country-specific proportions of several signs relative to each other,

country-specific sequence of signs, e.g., a succession of speed limit signs to cause the driver to gradually reduce the speed in front of a construction site (e.g., 120 km, 100 km, 80 km, 60 km),

country-specific presence or absence of particular signs or groups of signs, e.g., speed limit “80” or higher in England,

country-specific danger signs (e.g., bend, skidding conditions),

country-specific contents of traffic signs, e.g., place names,

recognition and interpretation of boundary signs, and

recognition and interpretation of information signs, e.g., signs located at national boundaries that indicate nationwide speed limits.

The first and second country estimation signals derived from these mentioned and detected features are particularly advantageously linked up by means of the microprocessor (designed as a merger module) in order to achieve a high degree of hitting accuracy, i.e., a high degree of probability with regard to determining the country in which the vehicle is traveling. For this purpose, the merger module weights and selects the two country estimation signals as input values and generates the actual country signal therefrom, said actual country signal indicating the country in which the vehicle is traveling.

Country-specific information (e.g., a country-specific speed limit on motorways/freeways) is made available to the driver by means of the country signal that is fed to a driver information device.

If such a country signal is made available to a driver assistance system, it is possible to comply with country-specific traffic laws and traffic rules, e.g., with the minimum distance to the vehicle ahead by means of an appropriate country-dependent parameterization in an ACC system.

Furthermore, an implicit speed limit may be determined by using such a country signal together with determining the road class (lane-relevant piece of information) and used for vehicle speed control by a driver assistance system.

Furthermore, the country signal, together with the position of the current lane that extends within the road (lane-relevant piece of information), may serve as additional information for a navigation system, for the warning strategy of an LDW assistance system or for an ACC assistance system. The statutory distance to the vehicle ahead can be complied with in a country-specific manner by means of an ACC system.

Further, advantages of the inventive method result from the possibility of performing a dynamic adaptation of algorithms to the country-specific conditions by means of the country signal so that the share of incorrect detections is reduced.

According to an advantageous further development of the invention, the image data of the environment sensor system are evaluated with regard to the recognition of license plates of motor vehicles in order to generate a third country estimation signal therefrom by means of an analysis by frequency, which third country estimation signal is fed to the merger module.

Since various functions for driver assistance systems are usually realized in different vehicle components, the country signal may be advantageously fed to a traffic sign recognition system in order to, e.g., select traffic sign classifiers depending on the country signal or to perform a parameter adaptation of image processing algorithms, e.g., detection thresholds, depending on the country signal, whereby detection performance is decisively enhanced while reducing the share of incorrect detections at the same time.

If the country signal is fed to a lane detection system of the vehicle, a dynamic adaptation of algorithms to the country-specific conditions may be performed in order to enhance detection performance also in this system while reducing the share of incorrect detections at the same time.

For example, the detection of Botts' dots may be restricted to the USA in order to avoid possible false warnings in other countries caused by Botts' dots recognition errors. A further advantage consists in the saving of computing time since special detector stages might be deactivated completely (e.g., Botts' dots detection, rectangular speed limit signs in the USA etc.).

Further advantages consist in the fact that a semantic interpretation of the scene can be derived correctly since

multiple markings in Japan and Europe sometimes have opposite semantic meanings so that modeling is only possible if some knowledge of the respective country is available, i.e., by means of the country signal;

a double marking can be interpreted correctly since, e.g., passing is only allowed where the marking is a broken line inside the lane and a solid line outside the lane;

a construction site can only be recognized correctly on the basis of the color of the marking depending on the country (e.g., yellow for construction site markings in Germany and for normal markings in the USA); and

the semantics of markings that are broken lines may differ from country to country and depends on, among other things, the blanking intervals/segment lengths (e.g., outer markings of freeways in Spain and France are often broken lines with long segments and short intervals).

Furthermore, it is particularly advantageous to determine, according to a further development of the invention, the unit of measurement (i.e., km/h or mph) of the numerical data detected on the traffic signs from the driving data of the vehicle, particularly from the traveling speed thereof and the detected traffic-sign-relevant information.

Furthermore, it is advantageous to detect, according to a further development of the invention, country-specific positions of the traffic signs lateral to the lane of the vehicle as well as relative to each other as traffic-sign-relevant information in order to, e.g., estimate therefrom whether vehicles drive on the left or on the right in the respective country in order to indicate this to the driver by means of the driver information device.

According to a further development of the invention, it is also advantageous to detect the color of the road lighting as a piece of lane-relevant information and to use it for the generation of the first country estimation signal.

Furthermore, it is advantageous to combine, according to a further development of the invention, countries having corresponding features in such a manner that these countries form a group of countries or a region so that, when lane-relevant and traffic-sign-relevant pieces of information are the same for several countries, a country signal that indicates these countries or a corresponding group of countries is generated by the merger module.

Storing the country signal in a non-volatile manner, particularly over a period of time between starting the vehicle engine and turning it off, is particularly advantageous.

A device for performing the inventive method is given by the features of one of the independent Patent claims 16, 17, 18 and 19, respectively.

In the following, the invention will be explained in greater detail with reference to the attached single figure. Said figure shows a block diagram of a device for performing an exemplary embodiment of the inventive method.

Said device that is installed in a vehicle comprises an environment sensor system 1 realized in the form of a camera, a lane detection system 2 with an associated first memory device 2 a, a traffic sign recognition system 3 with an associated second memory device 3 a, and a license plate recognition system 4 with an associated third memory device 4 a. These above-mentioned systems 2, 3 and 4 receive image data of the vehicle environment from the camera 1. The camera 1 is usually installed behind the windshield in the region of the inside rear-view mirror and is forward-directed so that both the pavement with the vehicles ahead and the verges are detected.

The lane detection system 2 comprises an image processing system that processes and evaluates the received image data. The image data of the camera 1 are evaluated with regard to lane-relevant information by comparing the detected lane-relevant information by means of data that are stored in the first memory device 2 a and that indicate country-specific lane markings and generating a country estimation signal S1 corresponding to the current location of the vehicle. Said country estimation signal S1 is fed to a merger module 5 that is usually designed as a microprocessor.

The traffic sign recognition system 3 also comprises an image processing system that processes and evaluates the received image data. The image data of the camera 1 are evaluated with regard to traffic-sign-relevant information by comparing the detected traffic-sign-relevant information by means of data that are stored in a second memory device 3 a and that indicate country-specific traffic signs and generating a second country estimation signal S2 corresponding to the current location of the vehicle. Said second country estimation signal S2 is also fed to the merger module 5.

Finally, the image data are also processed by the license plate determination system 4 and compared by means of the data that are stored in the memory device 4 a of the license plate determination system 4 and that indicate country-specific license plates of vehicles, and a third country estimation signal S3 is fed to the merger module 5. Alternatively, the device may be realized without such a license plate determination system 4.

From these three country estimation signals S1, S2 and S3, the merger module 5 determines a country signal L that is stored in a non-volatile memory 5 a of the merger module 5 at least over one period of time between starting the vehicle engine and turning it off. Said country signal L is fed to both a driver information device 6 and/or a driver assistance system 7, e.g., to an ACC system or a lane detection system that comprises, e.g., a lane keeping function and/or a lane change assistant. In particular, an ACC system can set the country-specific statutory distance to the vehicle ahead by means of the country signal and apply said distance to the corresponding control.

By means of such a driver information device 6, the driver traveling on, e.g., a freeway can be informed about the speed limit in force or about the traffic regulations and traffic rules that are in force in the respective country or about the unit of measurement (i.e., km/h or mph) of the speed indication.

Alternatively, the device according to FIG. 1 for performing the inventive method may be designed in such a manner that only the image processing system of the lane detection system 2 generates a country estimation signal S1 from which the merger module 5 generates a country signal L that is fed to both the lane detection system 3 and the license plate determination system 4.

According to a further alternative embodiment, the traffic sign recognition system 3, instead of the image processing system of the lane detection system 2, generates a country estimation signal 52 which is then fed, as a country signal L, to both the lane detection system 2 and the license plate determination system 4.

It is also possible to use only the license plate determination system 4, instead of the image processing system of the lane detection system 2, for the generation of a country estimation signal S3 so that the country signal L generated therefrom can be fed to the other systems, i.e., to both the lane detection system 2 and the traffic sign recognition system 3.

Finally, it is also possible that two of these three systems, i.e., the lane detection system 2 and the traffic sign recognition system 3 or the lane detection system 2 and the license plate recognition system 4 or the traffic sign recognition system 3 and the license plate recognition system 4, generate one country estimation signal each (S1 and S2 or S1 and S3 or S2 and S3) from which a country signal L is generated by means of the merger module 5.

REFERENCE NUMERALS

-   1 environment sensor system, camera -   2 lane detection system -   2 a first memory device -   3 traffic sign recognition -   3 a second memory device -   4 license plate determination -   4 a third memory device -   5 merger module, microprocessor -   5 a non-volatile memory of the microprocessor 5 -   6 driver information device -   7 driver assistance system 

1-4. (canceled)
 5. Method for supporting the driver of a road-bound vehicle in guiding the vehicle, in which the vehicle environment, in particular the markings that delimit the lanes of a road and traffic signs, are detected by an environment sensor system (1) and evaluated by an image evaluation system, characterized in that the image data of the environment sensor system (1) are evaluated with regard to the recognition of license plates of motor vehicles (4) and a country estimation signal (S3) is generated by an analysis by frequency, a country signal (L) that indicates the current location of the vehicle is generated from the country estimation signal (S3) by a microprocessor (5), and a driver information device (6) for outputting country-specific information regarding the longitudinal and transverse guidance of the vehicle is activated by the country signal (L) and/or the country signal (L) is fed to at least one driver assistance system (7) that supports the longitudinal and/or transverse guidance of the vehicle.
 6. Method according to claim 5, characterized in that the country signal (L) is fed to a traffic sign recognition system (3) and/or to a lane detection system (2) and/or to a license plate determination system (4). 7-17. (canceled)
 18. Device for supporting the driver of a road-bound vehicle in guiding the vehicle, in which the vehicle environment, in particular the markings that delimit the lanes of a road and traffic signs, are detected by an environment sensor system (1) and evaluated by an image evaluation system, characterized in that the image data of the environment sensor system (1) are evaluated with regard to the recognition of license plates of motor vehicles (4) and a country estimation signal (S3) is generated by an analysis by frequency, a country signal (L) that indicates the current location of the vehicle is generated from the country estimation signal (S3) by a microprocessor (5), and a driver information device (6) for outputting country-specific information regarding the longitudinal and transverse guidance of the vehicle is activated by the country signal (L) and/or the country signal is fed to at least one driver assistance system (7) that supports the longitudinal and/or transverse guidance of the vehicle.
 19. (canceled)
 20. Method for supporting the driver of a road-bound vehicle in guiding the vehicle, in which the vehicle environment, in particular the markings that delimit the lanes of a road and traffic signs, are detected by an environment sensor system (1) and evaluated by an image evaluation system, characterized in that the image data of the environment sensor system (1) are evaluated with regard to detected relevant information selected from traffic-sign-relevant information and lane-relevant information, the detected relevant information is evaluated relative to data that are stored in at least one memory device (2 a, 3 a) and that indicate country-specific traffic signs and/or lane markings, and at least one country estimation signal (S1, S2) corresponding to the current location of the vehicle is generated, a country signal (L) that indicates the current location of the vehicle is generated from the at least one country estimation signal (S1, S2) by a microprocessor (5), and a driver information device (6) for outputting country-specific information regarding the longitudinal and transverse guidance of the vehicle is activated by the country signal (L) and/or the country signal (L) is fed to at least one driver assistance system (7) that supports the longitudinal and/or transverse guidance of the vehicle.
 21. Method according to claim 20, wherein the detected relevant information comprises the lane-relevant information, and wherein the data indicate the country-specific lane markings.
 22. Method according to claim 21, characterized in that the country signal (L) is fed to a traffic sign recognition system (3) and/or to a license plate determination system (4).
 23. Method according to claim 20, wherein the detected relevant information comprises the traffic-sign-relevant information, and wherein the data indicate the country-specific traffic signs.
 24. Method according to claim 23, characterized in that the country signal (L) is fed to a lane detection system (2) and/or to a license plate determination system (4).
 25. Method according to claim 20, wherein: the detected relevant information comprises the lane-relevant information and the traffic-sign-relevant information, the detected lane-relevant information is evaluated relative to first said data that are stored in a first said memory device (2 a) and that indicate the country-specific lane markings, and a first said country estimation signal (S1) corresponding to the current location of the vehicle is generated, the detected traffic-sign-relevant information is evaluated relative to second said data that are stored in a second said memory device (3 a) and that indicate the country-specific traffic signs, and a second said country estimation signal (S2) corresponding to the current location of the vehicle is generated, and the country signal (L) that indicates the current location of the vehicle is generated from the first country estimation signal (S1) and the second country estimation signal (S2) by the microprocessor (5) which comprises a merger module.
 26. Method according to claim 25, characterized in that the image data of the environment sensor system (1) are evaluated with regard to the recognition of license plates of motor vehicles (4) and a third country estimation signal (S3) is generated by an analysis based on frequency, which third country estimation signal (S3) is fed to the merger module (5).
 27. Method according to claim 25, characterized in that the country signal (L) is fed to a traffic sign recognition system (3).
 28. Method according to claim 25, characterized in that the country signal (L) is fed to a lane detection system (2) .
 29. Method according to claim 20, characterized in that the unit of measurement (km/h, mph) of the numerical data detected on the traffic signs is determined from the driving data of the vehicle, particularly from the traveling speed thereof and the detected traffic-sign-relevant information.
 30. Method according to claim 20, characterized in that the traffic-sign-relevant information comprises country-specific positions of the traffic signs lateral to the lane of the vehicle as well as relative to each other.
 31. Method according to claim 20, characterized in that the color of the road is detected as a piece of lane-relevant information and used for the generation of the country estimation signal.
 32. Method according to claim 20, characterized in that when lane-relevant and/or traffic-sign-relevant pieces of information are the same for several countries, the country estimation signal or country signal that is generated indicates these countries or a corresponding group of countries.
 33. Method according to claim 20, characterized in that the country signal is stored in a non-volatile manner, particularly over a period of time between starting the vehicle engine and turning it off.
 34. Device for supporting the driver of a road-bound vehicle in guiding the vehicle, in which the vehicle environment, in particular the markings that delimit the lanes of a road and traffic signs, are detected by an environment sensor system (1) and evaluated by an image evaluation system, characterized in that the image data of the environment sensor system (1) are evaluated with regard to detected relevant information selected from traffic-sign-relevant information and lane-relevant information by at least one image processing system (2, 3), the detected relevant information is evaluated relative to data that are stored in at least one memory device (2 a, 3 a) of the at least one image processing system (2, 3) and that indicate country-specific traffic signs and/or lane markings, and at least one country estimation signal (S1, S2) corresponding to the current location of the vehicle is generated, a country signal (L) that indicates the current location of the vehicle is generated from the at least one country estimation signal (S1, S2) by a microprocessor (5), and a driver information device (6) for outputting country-specific information regarding the longitudinal and transverse guidance of the vehicle is activated by the country signal (L) and/or the country signal is fed to at least one driver assistance system (7) that supports the longitudinal and/or transverse guidance of the vehicle:
 35. Device according to claim 34, wherein the detected relevant information comprises the lane-relevant information, and wherein the data indicate the country-specific lane markings.
 36. Device according to claim 34, wherein the detected relevant information comprises the traffic-sign-relevant information, and wherein the data indicate the country-specific traffic signs.
 37. Device according to claim 34, wherein: the detected relevant information comprises the lane-relevant information and the traffic-sign-relevant information, the image data of the environment sensor system (1) are evaluated with regard to the lane-relevant information by a first said image processing system (2), the detected lane-relevant information is evaluated relative to first said data, that are stored in a first said memory device (2 a) of the first image processing system (2) and that indicate the country-specific lane markings, and a first said country estimation signal (S1) corresponding to the current location of the vehicle is generated, the image data of the environment sensor system (1) are evaluated with regard to the traffic-sign-relevant information by a second said image processing system (3), the detected traffic-sign-relevant information is evaluated relative to second said data that are stored in a second said memory device (3 a) of the second image processing system (3) and that indicate the country-specific traffic signs, and a second said country estimation signal (S2) corresponding to the current location of the vehicle is generated, and the country signal (L) that indicates the current location of the vehicle is generated from the first country estimation signal (S1) and the second country estimation signal (S2) by said microprocessor comprising a merger module (5). 